Diesel engines and equipment which use diesel fuel are, in many cases, preferred to machinery which use other types of fuel, e.g., trucks and boats used to haul freight are more often then not powered by diesel engines. Even though diesel engines are common, and have been common for many years, there continues to be problems with delivery, storage, and the optimized usage of diesel fuel in addition to problems with maximizing the efficiency of the diesel engine. Standard practice is to use No. 2 diesel fuel with diesel type internal combustion engines when ambient atmospheric temperatures are above about 10 degrees Fahrenheit and No. 1 diesel fuel when temperatures are below 10 degrees Fahrenheit. No. 2 grade diesel is the preferred fuel because it burns more efficiently than No. 1 grade, resulting in better engine performance. The particular problems with No. 2 grade diesel fuel include waxing or gelling of the fuel when atmospheric temperatures are below approximately 10 degrees Fahrenheit, which results in difficulty in starting cold engines, and less than complete combustion of the fuel, which in turn results in decreased engine efficiency and increased exhaust emissions. These problems stem from the fact that No. 2 grade diesel fuel has long chain hydrocarbons and waxes which form molecules that become progressively larger as temperatures decrease until the fuel will actually gell and wax at approximately 10 degrees Fahrenheit. Even when diesel fuel appears to be flowing readily, the hydrocarbon chains may be relatively long. Consequently, when the fuel is injected into the combustion chambers in the engine, the atomization of the fuel may be limited resulting in incomplete burning thereof.
Accordingly, it is known that preheating diesel fuel to prevent gelling and waxing by utilizing heated engine coolant and electric heaters and combining the preheater for the fuel with the engine coolant system will keep the engine warm during periods when the engine is not being used. It is also known that preheating aviation fuel prior to combustion in an engine will improve the burning characteristics of the fuel as well as heating diesel fuel as it enters a water separator will facilitate separating water from the fuel. Other prior art arrangements have dealt with control systems for controlling the flow of the engine coolant and energization of electric heaters, which may either be 12 volt or 120 volt. In some cases there has been a problem with direct contact of the diesel fuel with an electric heater and attempts to avoid this problem have resulted in arrangements which usually are complex and ultimately expensive to manufacture and maintain. It has also been found that fuel heaters which use engine coolant as a heat source and rely on a helical tube or tubing matrix of some arrangement within a chamber filled with heated engine coolant are usually inconsistent and heat fuel to substantially varying temperatures prior to the fuel exiting from the apparatus.
Many of these noted teachings are depicted and taught in some detail in the U.S. patents listed on the information disclosure form submitted simultaneously with this application. None of these prior art devices deals with the heating of fuel to a predetermined temperature range, which is close to the vaporization point for diesel fuel, or combines answers to the problems with delivery of fuel in a consistent manner in addition to keeping fuel warm and the engine warm during periods of non-use in a single device.
Accordingly, there exists a need for effective and economical solutions to the inherent problems of using diesel fuel, especially No. 2 grade diesel, with diesel type internal combustion engines.